How to compare two phone chargers by charge rate

One phone charger seems faster than another, but the battery percentage does not rise steadily. It can slow down as the battery fills, and the cable, phone temperature, or screen use can change the result too.

Use the Charger & Cable Test to compare the charging rate on the same phone. It reports the rate in percent per minute, which is useful for comparing setups, but it is not a measurement of charger wattage.

Compare the two chargers

Open the Charger & Cable Test in a browser on the phone you want to test. The test needs the browser to report the phone's battery status. If the tool is not available, that browser or device may not provide the required battery information.
Choose one cable and one wall outlet for both tests. Connect the first charger and check that the phone indicates it is charging.
Leave the phone idle and watch the charge rate in the test. Give it at least five minutes, since a brief reading can change as the phone updates its battery estimate.
Repeat with the second charger, keeping the phone, cable, outlet, and conditions the same. For a fair comparison, start both tests at about the same battery percentage, preferably within a few percentage points.
Run each test a second time if the readings are close or inconsistent. Compare the typical rates, not just the highest number you see.

It can be hard to begin two tests at precisely the same battery level. Do not drain the phone in a risky or inconvenient way to match a number. Wait for a later session when its charge is in a similar range.

What the result means

One charger has a consistently higher rate

If one setup repeatedly adds more battery percentage per minute under similar conditions, it charges your phone faster in that test. That does not prove the charger has a higher wattage in every situation. The phone and charger negotiate how much power to use, and the phone accepts only what it can support.

The rates are close

A small difference may come from rounded battery readings or normal changes in charging behavior. If the results overlap when you repeat the tests, treat the chargers as similar in this setup. The phone may also be limiting both chargers to the same rate.

Both rates are lower than expected

The battery may be nearly full, the phone may be warm, or the cable may be limiting the connection. A screen that stays on and demanding apps can also use some of the incoming power, making the battery percentage rise more slowly.

The test does not appear or shows no useful rate

Charger & Cable Test appears only on devices whose browser reports a battery, including some phones, tablets, and laptops. Try a different browser on the phone. If the browser still does not provide battery information, this browser test cannot compare the charge rate on that device.

How to make the comparison fair

Keep the cable the same. To compare chargers, use the same cable for both. A cable can affect charging, so changing it between tests makes it unclear whether the charger or cable caused the difference.
Start at a similar charge level. Charging rate often changes as the battery fills. Compare both chargers around the same percentage, such as 20 to 40 percent, rather than comparing one near empty with another nearly full.
Keep the phone cool and idle. Set it down in the same room, turn the screen off, and avoid games, navigation, or video playback while testing. If the phone is noticeably hot, let it cool before continuing.
Use the same power source. Plug each charger into the same wall outlet. For a charger with several ports, disconnect other devices so they do not change how power is shared between ports.
Test cable combinations separately. If you want to compare cables, use the same charger and phone, changing only the cable. To compare complete charging setups, test each charger with its own cable, then describe the result as a comparison of those combinations.

When a charger may be the problem

A low reading by itself does not show that a charger is broken. Repeat the test at a similar battery level, with a known compatible cable, and check whether the phone charges faster with another setup. Some phones charge quickly only with a supported charging standard, so a higher wattage printed on a charger does not guarantee a higher rate for your phone.

Stop using a charger or cable that is cracked, frayed, smells unusual, or becomes uncomfortably hot. If a charger repeatedly charges much more slowly than a compatible alternative under the same conditions, check the phone and charger makers' compatibility information or replace the suspect charger. This test compares charging behavior; it does not verify electrical safety or measure exact watts.

Nothing in this test requires you to record or upload files. The rate is a comparison aid, not a substitute for the phone's charging indicator or the charger's specifications.